Construction and earthmoving equipment as well as a wide variety of other types of work machines are commonly used in a wide variety of different types of construction and earthmoving applications. These work machines typically include a wide variety of hydraulically actuated implements and/or work attachments such as buckets, front shovels, scrapers and the like which are utilized in different applications to accomplish different tasks. The control and operation of these various implements and/or work attachments preferably have a be timely response to the operator input commands controlling the operation thereof without sacrificing performance or power.
Sometimes a delay in implement or work attachment responsiveness may occur during a particular work application due to the fact that the hydraulic pump servicing the operation of the particular implement cannot provide the necessary amount of fluid flow to the implement actuator means as requested by the operator. For example, this may occur when an implement such as a blade on a track type tractor is rapidly lowered to the ground and the operator input is thereafter immediately actuated to lower the blade into the ground. For example, if the blade is raised above the ground line, then lowered, the blade will rapidly lower to the ground due to gravity. The rapid lowering movement will cause the cylinder to void. Further lowering of the blade is delayed until the pump fills the void in the cylinder. The delay typically occurs because during this rapid movement the hydraulic pump servicing the particular hydraulic circuit will be providing a large amount of fluid to the actuating means controlling the movement and operation of the implement or work attachment. Where the implement actuating means is a hydraulic cylinder, the hydraulic pump will provide fluid flow to either the head end portion or the rod end portion of the hydraulic cylinder to control the extension or retraction thereof. When fluid flow is provided to the rod end portion of the cylinder thereby retracting the same, fluid present in the head end portion is contracted and allowed to exit therefrom under pressure and escape to other portions of the circuit In the example where a blade associated with a track type tractor is rapidly lowered at low pressure, the hydraulic pump will be providing a large amount of fluid to the head end portion of the actuating cylinder. When the cylinder is then requested to move immediately in the same direction at high pressure, the hydraulic pump is unable to provide enough fluid flow to the head end portion of the cylinder in order to meet the responsiveness desired by the operator. In other words, the head end portion of the actuating cylinder is not refilled, or regenerated, fast enough to achieve the desired responsiveness.
Although some hydraulic control systems employ a regeneration circuit to fill the expanding side of a hydraulic cylinder or other actuator means with fluid exhausted from the contracting side, it would be desirable to provide a regeneration circuit which would be more responsive to certain parameters which are indicative of the operator requesting a rapid movement of the actuator means associated with a particular implement or work attachment. In this regard, it would also be desirable to provide a regeneration circuit which will increase the efficiency of filing the expanding side of a hydraulic actuating cylinder.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.